amplifying / research
Edwin Ong & Alex Vikati ·
Every Vendor and Tool We Found
Hardcoded in Claude Code
We searched Claude Code's leaked source for every hardcoded vendor reference. 120+ companies across six systems. Here is what we found.
37
MCP servers
6
hosted
89
domains
25+
platforms
23
secrets
7
gateways
The sources
Six files, six integration layers
Claude Code's leaked source is ~512,000 lines of TypeScript. We searched the full tree and found vendor names hardcoded in six distinct files, each serving a different purpose.
There may be vendor references in other files we did not inspect. This is every reference we could find.
The map
Six systems, six different meanings
MCP UI Allowlist
Tool output collapses into clean summaries
37 servers
Anthropic-Hosted MCP
Proxied through mcp-proxy.anthropic.com
6 servers
WebFetch Preapproved
Docs fetchable without user-provided URL
89 domains
Environment Detection
Analytics telemetry for deployment platforms
25+ platforms
Secret Scanner
Credential formats blocked from team memory
23 patterns
API Gateway Detection
Third-party proxy traffic identified
7 gateways
None of this changes which tools Claude recommends. All of it changes how vendors are treated inside the product.
System 1 · MCP UI Allowlist
The 37 servers with first-class UI
Sorted by number of classified tool operations (search + read).
+ 24 more: Linear, Playwright, MongoDB, AWS, Filesystem, Exa, Obsidian, Neo4j, Git, Firecrawl, BigQuery, Gmail, Google Calendar, Perplexity, Tavily, Notion, Elasticsearch, Airtable, Terraform, Memory, Google Drive, SQLite, Brave Search, Figma
System 1 · Key pattern
The DevOps cluster dominates
117
DevOps + Infra tools
Datadog · Grafana · PagerDuty
Sentry · Kubernetes
84
PM tools
Linear · Notion · Asana
Atlassian
Anthropic has invested more UI code in making “check the dashboard” and “read the logs” work cleanly than in making “check the backlog” work cleanly. Claude Code is built for the observe-debug-fix loop.
System 2 · Anthropic-Hosted MCP
6 servers Anthropic runs for you
Slack
14 tools
PubMed
18 tools
Gmail
6 tools
Google Calendar
6 tools
BigQuery
6 tools
Google Drive
3 tools
If you are included
Zero-config for users. OAuth-managed. No local MCP process, no API keys, no token refresh. Click 'Connect' and it works.
If you are not
Users configure your server locally — install packages, set env vars, manage tokens. Every step is a drop-off point.
System 2 · Deep dive
Slack gets the deepest treatment of any vendor
Compact UI rendering
trySlackSendCompact() renders message sends as one-liners with #channel and archive links
Custom OAuth error handling
Slack returns HTTP 200 for errors (violating RFC 6749). Claude Code normalizes invalid_refresh_token → invalid_grant
Deduplication logic
If both local and hosted Slack servers are configured, local takes precedence. User control preserved.
This is the kind of investment you make for a partner, not an afterthought.
System 3 · WebFetch Preapproved Domains
89 domains Claude Code can fetch on its own
A security allowlist for GET requests. Claude Code can read these docs without the user providing a URL.
AWS+ 74 more: Python, C++, Java, TypeScript, Go, PHP, Swift, Kotlin, Ruby, Angular, Vue.js, Express, Bun, jQuery, Bootstrap, Webpack, Jest, Flask, Pandas, NumPy, TensorFlow, scikit-learn, Laravel, Symfony, WordPress, Hibernate, Maven, Gradle, .NET, React Native, Flutter, MongoDB, Redis, PostgreSQL, MySQL, SQLite, GraphQL, Prisma, Terraform, Ansible, Heroku, Cypress, Selenium, Unity, Unreal, Git, Nginx, and more.
If you are included
The agent can proactively pull your docs, API references, and guides during real-time reasoning. Your product is more legible when it matters.
If you are not
Claude Code can still fetch your docs, but only when the user pastes a URL. You are invisible to the fetch layer by default.
Notable absences
Where Vercel, Cloudflare, and Docker appear instead
These vendors have no MCP UI collapsing, but they show up in other systems:
Vercel
Only vendor with an official plugin tip
Cloudflare
Workers frequently recommended but no MCP UI
Docker
Foundational infra, no MCP server classified
GitLab
CI/CD outside GitHub is not instrumented
Systems 5 & 6 · Secrets + Gateways
The safety and observability layers
Secret scanner — 23 credential patterns
AWS
Shopify+ 13 more: GCP, Azure, DigitalOcean, Hugging Face, Twilio, SendGrid, Databricks, Terraform, Pulumi, Postman, NPM, PyPI
API gateway detection — 7 gateways
Detected via response headers or hostnames. Purely observational for analytics.
Key takeaways
What this means for vendors
MCP UI = distribution advantage
Listed servers get collapsed, readable output. Unlisted servers dump raw JSON. In multi-step sessions, that UX gap compounds.
Hosted = zero-friction adoption
Only 6 vendors get OAuth-managed proxied infrastructure. Everyone else requires local setup with drop-off at every step.
DevOps > PM in investment
117 DevOps tool classifications vs 84 PM tools. Anthropic expects Claude Code to live in the observe-debug-fix loop.
The list is manual — it won't scale
Each tool name is typed by hand into a Set object. Either Anthropic moves to convention-based classification, or this becomes a de facto ranking.
Alternative paths exist
Vercel has no MCP UI support but has the only third-party plugin tip. Different distribution channel, same destination.
Being named matters at every layer
Preapproved docs, env detection, secret scanning — each is a different kind of visibility in the system that millions of developers use daily.
Read more
Read the Full Analysis
The full article includes every vendor badge, the complete cross-reference table, code walkthroughs, and detailed implications for each system.
All source code referenced is the intellectual property of Anthropic, PBC. This analysis is published for educational and research purposes only.